Device for actuating at least a piston and method for detecting failure in a device

ABSTRACT

A device ( 1 ) for actuating at least one piston ( 2 ) moving axially in the bore ( 3 ) of a body( 4 ), the piston ( 2 ) being driven by the longitudinal or curved movement (F 2 ) of a control arm ( 5 ). Also disclosed is a method for detecting a failure in a device ( 1 ) having an intermediary element ( 6 ), located between the piston ( 2 ) and the control arm ( 5 ), this intermediary element ( 6 ) being also used as an alarm means should the intermediary element ( 6 ) be missing between the piston ( 2 ) and the arm ( 5 ). The invention is particularly applicable in the field of diagnosis.

DESCRIPTION

[0001] This invention concerns a device for actuating at least onepiston moving axially in the bore of a body, the piston being driven bya longitudinal or curved movement of a control arm. The invention alsoconcerns a method for detecting a failure in such a device.

[0002] Prior art consists of apparatuses in which the piston co-operateswith a control arm through an intermediary element such as a ball. Twocases are to be considered. In the first case, the ball cannot exit therecess where it is located, whether it be through crimping or specialconstruction (stop, flange, wedge, . . . ).

[0003] However, this kind of apparatus is more expensive to manufacturedue to the additional operations to be performed at the time ofinstallation and to the additional components that are required. Inaddition, should a problem occur, disassembling the apparatus is moredifficult since there is a greater number of components and additionalitems are required for fastening said components to one another.

[0004] In the second case, the ball is free, that is to say it is placedat the location where it must be active, and is simply centered by knownmeans such as blind hole, through hole with two different diameters, ormachined boss, . . .

[0005] The main disadvantage of this embodiment lies in the possibleloss of the ball, which causes the piston movement to stop, and forcesthe piston to remain inactive. This problem may be especially annoyingin automated devices, e.g. automated biological diagnosis devices, inwhich the piston is associated with a syringe or a pipette enabling abiological liquid to be sampled. In this kind of automated device, oneoften finds several pistons arranged in parallel and the assembly isenclosed within a housing that does not allow the device's operation tobe viewed. Moreover, if each piston is not associated to a sensor meantfor detecting its activation, which is very expensive, a failure causedby the loss of the ball cannot be detected insofar as the absence of theball does not prevent the automated device from operating. This mayinduce false negative or positive results, with possibly quite harmfulconsequences for the patients.

[0006] In accordance with this invention, the proposed device and methodare intended to overcome these disadvantages.

[0007] To this end, this invention concerns a device for actuating atleast one piston moving axially in the bore of a body, the piston beingdriven by the longitudinal or curved movement of a control arm,characterized in that it has an intermediary element, located betweenthe piston and the control arm, this intermediary element also beingused as an alarm means should said intermediary element be missingbetween said piston and said arm.

[0008] According to an alternate embodiment, when the intermediaryelement is missing between the piston and the arm, this element is incontact with a recovering means, this contact being detectable.

[0009] According to another alternate embodiment, the intermediaryelement is missing between the piston and the arm as a result of theattractive action of a recovery means and/or the ejection effectproduced by a dislodging means on said element.

[0010] According to a first embodiment, the intermediary element is aball.

[0011] According to a second embodiment, the intermediary element is ametal ball and the recovery means is a magnet.

[0012] According to the alternate embodiment, and regardless of theembodiment, the recovery means is associated with a recess whichfacilitates the recovery of the element.

[0013] Yet still according to the alternate embodiment and regardless ofthe embodiment, the recovery means and/or the recess is(are) associatedwith the control arm.

[0014] Preferably, the recovery means and/or the recess is(are) locatedbetween two adjacent intermediary elements.

[0015] Regardless of the embodiment, the dimensions of the intermediaryelement, and notably the ball diameter, are greater than the distanceseparating the body from the control arm, at the level of the recoverymeans, when they are close to one another.

[0016] This invention also concerns a method for detecting a failure ina device, as described above, the method consisting in operating thedevice in a normal way and detecting abnormal kinematics of said device.

[0017] Preferably, the detection of abnormal kinematics of the device isdue to the presence of the intermediary element located between the bodyand the control arm of said device, notably at the level of the recoverymeans.

[0018] The accompanying drawings are given by way of example and are notto be taken as limiting in any way. They are intended to make theinvention easier to understand.

[0019]FIG. 1 represents a partial cross-sectional view showing the upperportion of two pistons, each piston being in position before beingactuated by balls, in turn actuated through a control arm, according toa specific, yet representative, mode of prior art.

[0020]FIG. 2 represents a partial cross-sectional view according to///FIG. 1, when the control arm actuates the pistons and when there is noproblem with the movement transmission balls.

[0021]FIG. 3 represents a partial cross-sectional view according to///FIG. 1, when the control arm actuates the pistons and when there is aproblem with the movement transmission balls, as one of the balls hasescaped.

[0022]FIG. 4 represents a partial cross-sectional view of a firstembodiment of this invention, showing the upper portion of two pistons,each piston being in position before being actuated by balls, in turnactuated through a control arm.

[0023]FIG. 5 represents a partial cross-sectional view according to FIG.4, when the control arm actuates the pistons and when there is noproblem with the movement transmission balls.

[0024]FIG. 6 represents a partial cross-sectional view according to///FIG. 4, when the control arm actuates the pistons and when there is aproblem with the movement transmission balls, as one of the balls hasescaped.

[0025]FIG. 7 represents a partial cross-sectional view of a secondembodiment of this invention, showing the upper portion of two pistons,each piston being in position before being actuated by balls, in turnactuated through a control arm.

[0026] Finally, FIG. 8 represents a partial cross-sectional viewaccording to/// FIG. 7, when the control arm actuates the pistons andwhen there is a problem with the movement transmission balls, as one ofthe balls has escaped.

[0027]FIGS. 1 through 3 represent the closest prior art known to theapplicant. In this prior art, the device 11 makes it possible to actuateat least two mobile pistons 12 located in two parallel bores 13. Thesebores 13 are made in the body 14 of said device 11.

[0028] The upper face 17 of each piston 12 has a centering means 18usually consisting of a concave recess 18 which is cone-shaped but mayalso have different shapes. This centering means 18 receives anintermediary element 16 which consists of a ball 16, according to theembodiment of prior art presented in FIGS. 1 through 3. The diameter ofthe ball 16 is less than that of the piston 12, in turn less than thatof the bore 13.

[0029] The assembly made up of the ball 16 and the piston 12 can thusmove in the direction of the arrows F1 and F2. The movement in thedirection of F1, i.e. when the mobile piston 12 moves away from acontrol arm 15, is driven by any known means in prior art, such as arecoil spring, for example. The movement in the direction of F2, i.e.when said mobile piston 12 moves closer to the control arm 15, isperformed by simply moving the control arm 15. This movement in thedirection of F2 may be longitudinal, i.e. coaxial with the direction ofthe movement that will be generated on the piston 12, or curved if, forexample, the control arm 15 is installed on the body 14, directly orindirectly, through an articulation or rotation axis not shown in thefigures.

[0030] It is clear that, when the balls are present, there is noproblem, and the two pistons will be moved in the direction of F2, as iswell shown in FIG. 2.

[0031] On the other hand, when one of the balls 16 has gotten away,which is the case shown in FIG. 3, one can note that the control arm 15has moved down in the direction of F2 and only pushed down the piston12, on the left side of the figure. The piston 12 on the right side ofthe figure did not move at all. Yet, the absence of the ball did nothamper the movement of said arm 15. Therefore, neither the user nor thesoftware that implements the device 11 can detect that said ball 16 ismissing.

[0032] According to this invention, the whole set of features quoted forFIGS. 1 through 3 applies to FIGS. 4 through 6 for the first embodimentof this invention and to FIGS. 7 through 8 for the second embodiment ofthis invention. Nonetheless, the numbers differ slightly. 5

[0033] In this manner, according to the first embodiment of theinvention, one finds again the device 1 that enables the two mobilepistons to be actuated. Each mobile piston 2 is housed in a bore 3provided within the body 4 that makes up the device 1 together with thecontrol arm 5. The intermediary element is referenced 6 and it alsoconsists of a ball 6. The upper surface 7 of the piston 2 also has acentering means 8, the structure of which is substantially identical tothat of the means shown in FIGS. 1 through 3.

[0034] Still according to FIGS. 4 through 6, one can note, however, thatthere is a substantial change that enables the method according to theinvention to be implemented. This structural difference defines thedevice 1 according to this invention against the device 11 in prior art.This way, one can note that the lower face in FIGS. 4 through 6 of thecontrol arm 5 features a recess 10 which is located between the twoballs 6 of the two pistons 12 located close to one another.

[0035] At the bottom of the recess 10, there is a means 9 for recoveringthe intermediary element 6. According to a preferred embodiment, thisrecovery means 9 consists of a magnet 9. In that case, the ball 6 ismade of metal in order to co-operate with the magnet 9 if leaks occur,in the direction of F3 as is well shown in FIG. 6.

[0036] It is clear that, when the ball 6 is between the body 4 and thecontrol arm 5, near the recovery means 9, the ball 6 will prevent saidarm 5 from moving down in the direction of F2, which will tend todisrupt the kinematics of the arm 5. In such a case, it will be mucheasier for the user or the software that controls the device 1, todetect a malfunction and to quickly diagnose the reasons for thismalfunction.

[0037] According to the second embodiment, shown in FIGS. 7 and 8, itcan be seen that the first embodiment in FIGS. 4 through 6 can beprovided with an enhancement which further improves the dislodging ofthe ball 6 in the direction of F3 and the detection of said ball 6 dueto its wedging between the body 4 and the control arm 5 of the device 1according to the invention. In this second embodiment, a means 19 fordislodging the element 6, in the form of a spring, is present andfacilitates the expulsion/// in the direction of F3 of said elementtowards the recovery means or magnet 9. This dislodging means 19consists of a spring 19 that is lodged in a housing 20. When the ball 6is present between the control arm 5 and the centering means 8 locatedat the surface 7 of the piston 2, the spring 19 is subjected to a lowcompression, e.g. a few tens of grams, while the pressure exerted bysaid arm 5 is greater, that is to say it ranges from 100 grams to a fewkilograms.

[0038] The orientation of the spring 19, and therefore that of thehousing 20, is such that when the ball 6 can escape in the direction ofF3, said spring 19 is no longer constrained by the arm 5 and thereforethe ball 6 can escape towards the magnet 9. To this end, thelongitudinal axis of said spring 19, and thus that of said housing 20,crosses the recovery means 9. In the embodiment of FIGS. 7 and 8, arecovery means 9 is present between the two balls 6, and the two relatedsprings 19 have longitudinal axes that cross each other. It is alsopossible that a recovery means 9 be associated with a single ball 6.

REFERENCES

[0039] 1. Device for actuating at least one mobile piston 2 according tothe invention

[0040] 2. Mobile piston according to the invention

[0041] 3. Bore in the body 4 where the piston 2 moves according to theinvention

[0042] 4. Body of the device 1 according to the invention

[0043] 5. Control arm of the device 1 according to the invention

[0044] 6. Intermediary element or ball according to the invention

[0045] 7. Upper surface of piston 2 according to the invention

[0046] 8. Centering means of the element 6 on the surface 7 according tothe invention

[0047] 9. Means for recovering the element 6 or magnet according to theinvention

[0048] 10. Recess near the recovery means 9 according to the invention

[0049] 11. Device for actuating at least one mobile piston 12 accordingto prior art

[0050] 12. Mobile piston according to prior art

[0051] 13. Bore in the body 14 where the piston 12 moves according toprior art

[0052] 14. Body of the device 11 according to prior art

[0053] 15. Control arm of the device 11 according to prior art

[0054] 16. Intermediary element or ball according to prior art

[0055] 17. Upper surface of the piston 12 according to prior art

[0056] 18. Centering means of the element 16 on the surface 17 accordingto prior art

[0057] 19. Means for dislodging the element 6 or spring according to theinvention

[0058] 20. Housing containing the means 19

[0059] F1. Direction of the movement of the control arm 5 or 15 whenmoving away from the mobile piston 2 or 12

[0060] F2. Direction of the movement of the control arm 5 or 15 whenmoving closer to the mobile piston 2 or 12

[0061] F3. Dislodging of element 6

1. A device (1) for actuating at least one piston (2) moving axially inthe bore (3) of a body (4), the piston (2) being driven by thelongitudinal or curved movement (F2) of a control arm (5), characterizedin that it has an intermediary element (6), located between the piston(2) and the control arm (5), this intermediary element (6) also beingused as an alarm means should said intermediary element (6) be missingbetween said piston (2) and said arm (5).
 2. The device according toclaim 1, characterized in that, when the intermediary element (6) ismissing between the piston (2) and the arm (5), this intermediaryelement (6) is in contact with a recovery means (9), this contact beingdetectable.
 3. The device according to either of claims 1 or 2,characterized in that, when the intermediary element (6) is missingbetween the piston (2) and the arm (5) as a result of the attractiveaction exerted by the recovery means (9) and/or the ejection effect ofsaid element (6) by a dislodging means (19).
 4. The device according toany of claims 1 through 3, characterized in that the intermediaryelement (6) is a ball (6).
 5. The device according to any of claims 2through 4, characterized in that the intermediary element (6) is a metalball (6) and the recovery means (9) is a magnet (9).
 6. The deviceaccording to any of claims 2 through 5, characterized in that therecovery means (9) is associated to a recess (10) which facilitates therecovery of the element (6).
 7. The device according to any of claims 2through 6, characterized in that the recovery means (9) and/or therecess (10) is(are) associated with the control arm (5).
 8. The deviceaccording to any of claims 2 through 7, characterized in that therecovery means (9) and/or the recess (10) is(are) located between twoadjacent elements (6).
 9. The device according to any of claims 1 or 8,characterized in that, when the dimensions of the intermediary element(6), and notably the diameter of the ball (6), are greater that thedistance between the body (4) and the control arm (5), near the recoverymeans (9), when the body (4) and the control arm (5) are moved closer(F2) to one (4) another (5).
 10. The method for detecting a failure in adevice, according to any of claims 1 through 9, characterized in that itconsists in operating the device (1) in the normal way and in detectingan abnormal kinematics of the latter (1).
 11. The method, according toclaim 10, characterized in that the detection of abnormal kinematics ofthe device (1) is due to the presence of an intermediary element (6)located between the body (4) and the control arm (5) of said device (1),notably near the recovery means (9).